Bans for felonies are lifetime.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.
I suggest you get your firearms rights restored. To do that you would have to have your conviction removed from your record, expunged or otherwise changed so that you can now own and possess firearms. To do this you would have to contact a South Carolina criminal defense or gun rights attorney.
The above information does not establish an attorney client relationship nor is it meant to provide legal advice.
All three of the other responses when put together generally give you the answer to your question. A felony conviction generally bars you from owning firearms for life under federal law. That means, that if at anytime you are found in possession of either a firearm or ammo (even a single round), you can be charged with another felony. Therefore, you should not be currently in possession of either. If you have been in the past and you are worried about when the statute of limitations runs, I believe it is three years, but I am not certain and you should no rely on that.
As noted by my colleague, you may be able to have the felony set aside and your rights restored, but that depends on South Carolina law. Yyou should speak with a South Carolina attorney about that.
If you would like any additional information about firearm laws and rights restoration, there is a ton of it on my firm's website. Good luck.
Michel & Associates, PC
All my comments here are intended for general legal purposes. None of my comments here establish an attorney-client relationship with anyone. None of my comments should be relied on in taking legal action without first consulting an attorney.